Machine for sharpening taps

ABSTRACT

A DEVICE FOR GRINDING FLURTES OF TAPS, HAVING A VERTICALLY ADJUSTABLE, VERTICALLY DISPOSED GRINDING WHEEL AGAINST THE PERIPHERY OF WHICH THE TAP TO BE GROUND CAN BE MOVED. A TURRET FOR HOLDING THE TAP IS ADJUSTABLE ABOUT A HORIZONTAL AXIS, ABOUT A VERTICAL AXIS, AND IN A LATERAL PATH PARALLEL TO THE AXIS OF THE GRINDING WHEEL. WITHIN ADJUSTABLE LIMITS, THE TURRET WITH THE TAP IS MOVABLE BACK AND FORTH TO BRING THE TAP INTO CONTACT WITH THE GRINDING WHEEL FOR THE GRINDING ACTION TO TAKE PLACE AT THE PROPER ANGLE TO THE TAP. GRADUATIONS ARE PROVIDED TO INDICATE THE APPROPRIATE ANGULATITIES. THE MACHINE IS ADJUSTABLE TO OPERATE WITH DIFFERENT SIZES OF TAPS, DIFFERENT SHAPES OF GRINDING CUTS, AND DIFFERENT NUMBERS OF FLUTES.

N0 30, 1971 l.. w. GREENBLATT 3,623,271

MACHINE FOR SHARPENING TAPS Filed June 4, 1969 2 Sheets-Sheet 1 I'IIII'II H4 I'III'IIIII LOUIS W GREENBLATT M ,MW 49 /4/ i A TORNEYS NGV. 30, 1971 L. w. GREENBLATT 3,623,271

MACHINE FOR SHARPENING TAPS 2 Shoots-Shoot Filed June 4, 1969 FIG.6

v32S INVENTOR LOUIS w GREENBLATT United States Patent O 3,623,271 MACHINE FR SHARPENING TAPS Louis W. Greenblatt, 12 Ladue Manor, St. Louis, Mo. 63124 Filed .lune 4, 1969, Ser. No. 830,313 Int. Cl. B24b 3/18 U.S. Cl. 51-92 ND 5 Claims ABSTRACT OF THE DISCLOSURE A device for grinding flutes of taps, having a vertically adjustable, vertically disposed grinding wheel against the periphery of which the tap to be ground can be moved. A turret for holding the tap is adjustable about a horizontal axis, about a vertical axis, and in a lateral path parallel to the axis of the grinding wheel. Within adjustable limits, the turret with the tap is movable back and forth to bring the tap into contact with the grinding wheel for the grinding action to take place at the proper angle to the tap. Graduations are provided to indicate the appropriate angularities. The machine is adjustable to operate with different sizes of taps, different shapes of grinding cuts, and different numbers of flutes.

SUMMARY OF THE INVENTION The invention consists of the arrangement of a grinding wheel for grinding utes in taps which can be adjusted vertically to dispose the grinding wheel at different elevations with respect to a base, and to provide a chuck or collet for the tap to be ground which can be adjusted laterally with respect to the grinding wheel, and angularly with respect to both a vertical and a horizontal plane. Additionally, the machine is adjustable toA accommodate different sizes of taps to be ground and taps with different numbers of flutes so that once it is set up with the proper angularity, all of the successive flutes can be ground with no readjustment other than a simple guided and limited angular movement of the tap in its support to introduce the utes successively to grinding positions, and the inand-out movement to cause the tap to pass into contact with the grinding wheel. A further feature is the disposition that provides for application of different grinding wheels so that different shapes and sizes of cuts may be made. Further features will appear from the full description to follow.

In the drawings:

FIG. l is a side elevation of the tap Sharpener;

FIG. 2 is a plan view thereof;

FIG. 3 is a vertical section taken on the line 3 3 of FIG. 1 showing a vertical adjusting means;

FIG. 4 is a vertical section taken on the line 4-4 of FIG. l showing a side-to-side or lateral adjusting means;

FIG. 5 is a section on the line 5-5 of FIG. 2 showing an in-and-out or forward and backward tracking means;

FIG. 6 is a section on the line 6-6 of FIG. 2 showing the chuck and means for its adjustment about a horizontal and about a vertical axis;

FIG. 7 is a section on the line 7-7 of FIG. 6 showing detent means for use with taps having different numbers of utes;

FIG. 48 is a view of the end of a tap showing the axis along which the sharpening grinding action takes place; and

FIG. 9 is an end view of a tap showing one grinding wheel in its sharpening position.

The machine of the present invention positions a tap and a grinding wheel so as to permit easy grinding of the flutes 16 of taps of various sizes and kinds.

The machine includes a rectangular base 20 onto which a pedestal 21 is secured by bolts 22. These parts are made FPice of strong material such as a good grade of steel or cast iron.

T-wo upstanding bearing blocks 23- and 24 are provided on the top surface of the base 20 to be integral therewith. Two round parallel tracking bars 25 are securely mounted on the bearing blocks 23 and 24 above the upper surface of the base 2.0, and are held in place by hold-down clamps 26.

A tap-holding head generally designated 30` is mounted for in-and-out sliding movement on the track bars 25, and for lateral movements transversely thereto. For this latter purpose a slide block 33 is mounted for in-and-out movement on the rods 25, being freely movable thereon but held with minimal lost motion by linear ball bearing 34. A limit or stop bar 36 is secured on the slide block 33, and is threaded on its ends to receive stop members 37 and 38, which can be adjustably positioned along the respective ends of the bar. The bar 36 passes through the support blocks 23 and 24 of the head 30, and the stops 37 and 38 limit the travel forward and backward by striking the support blocks 23 and 24.

The guide block 33 supports a platen 40` for lateral movement across the block 33 but without fore and aft movement. To this end a key 41 is mounted in an appropriate key slot in one of the two, and slides in a groove in the other. Also shouldered screws 43, threaded into the block 33, and engaging over Belleville spring washers 45, ride in slots 44 in the platen 40 to hold it onto the slide block 33 and to apply predetermined friction between the parts. Other means of connecting these parts for this sliding movement could be used, provided it attains a dovetail effect.

Sliding movement of the platen laterally as guided by the key 41 is effected by a feed screw 46, mounted through a flange 47 extending from one edge of the platen 40. The screw 46 is retained against axial movement by an internally threaded knob 48 threaded onto the screw 46 externally of the flange and a retaining nut 49 secured firmly to the screw internally of the flange. The knob 48 is keyed onto the feed screw 46 by a set screw or pin 50, and is held in adjusted position also by a jam nut 51. Thus rotating of the Iknob 48 will turn the feed screw 46 but will not move the same axially with respect to the platen.

The feed screw is threaded into an appropriately threaded opening that extends transversely through the guide block 33 so that rotation of the knob 48 and the feed screw 4-6 displaces the platen 40` laterally one way or the other with respect to block 33 as guided by the key 41.

The platen 40` supports a turret generally indicated at 56, the same being rotatably mounted on the upper surface of the platen about a central sc-rew 57. A fastening nut `58 with a projecting handle 59 can be loosened to permit free rotation of the turret, or tightened to hold the turret in a selected position. Appropriate graduations 60 on the edge of the turret base can cooperate with an index 61 on the platen to indicate the angular position of the turret with respect to the fore-and-aft axis.

The turret has a flat-sided shank 62 over which is mounted a bifurcated turret head 64, the same having depending parallel sides 65 to embrace the opposite flat sides of the shank 62. A screw 66 passes through the shank 62 and the flanges 65, and can have an appropriate handle for releasing it and tightening it so that the turret head 64 may be adjusted to dilferent angular positions about the center of the screw 66, and then fastened in position. An appropriate set of graduations 68 are provided on the turret shank 56 and cooperate with the lower edge of the bifurcated member 64 so that the angular position can be readily read.

The head 64 is adapted to provide and support a chuck 69 for holding the tap 15 that is to be ground. To this end there is a round shaft 70 that is rotatably supported in a hole through the head 64. A collar 71 is held by a set screw or pin 72 onto a reduced portion of the shaft 70, to limit its rearward axial movement. The other end of the shaft 70 extends to the rear 0f the head 64 and has a collar 73 around it. The head 64, as particularly shown in FIGS, 6 and 7, has a spring-urged ball and socket detent 75 that can engage in any of a number of sockets 76 in the collar 73. These sockets 76 are arranged so as to provide 90 and 120 displacements for grinding two-tinted, three-iluted, or four-tinted taps. A set screw 78 is engageable in a groove 79 that surrounds the shaft 70. The set screw 78 is normally turned down so that the collar 73 rotates with the shaft 70, but it can be loosened for adjustment and calibration purposes. A knurled knob 80 is secured firmly to `the shaft 70 by a set screw or pin 81, in such a way that there is no axial movement of the shaft 70 in the head 64. The knob 80 can be turned to rotate the shaft.

The tap-receiving chuck or collet 69 is mounted on the end of the shaft 70 and has conventional releasable means for holding the tap 15.

It will be readily apparent that a tap supported in the chuck 85 can be positioned at a desired angle to the horizontal and also a desired fore-and-aft angle. It can be adjusted laterally and held in adjusted position; and it can be moved fore and aft within predeterminable limits.

The pedestal 21 is adapted to hold a grinding wheel for adjustment vertically. The pedestal has upper and lower pairs of V-notched forwardly projecting ledges 100 and 101. These receive guide bars 102 supported in position by the V-notches and clamped firmly by cross members 104 and 105 at the upper and lower positions, respectively. The cross bars are held in position by screws 106 that pass through them into the pedestal.

The bars 102 constitute supporting guides for a crosshead 110, which has appropriate bushings 111 to provide smooth vertical motion of the cross-head without lost motion. An adjusting screw 112 has a reduced upper end passing through a projection 113 on the pedestal and into a knob 1114 that is knurled so that it can be readily rotated. The screw receives a nut 115 which acts as a lock nut to hold the knob 114 on the screw, the whole assembly permitting the screw to be rotated without axial movement, to move the cross head 110 vertically.

The cross head supports an electric motor 120, the shaft of which receives a grinding wheel of appropriate size and shape 121. As will be understood, different sizes and shapes of grinding wheels may be substituted on the motor shaft.

OPERATION A tap 15 to have its flute ground is secured in the chuck 69. The flute has two angular relationships to the axis of the tap, one of them being a lateral angle and the other being an angle to the horizontal. The lateral angle is that illustrated in FIG. 8, whereas the horizontal angle can be seen in FIG. 6 and causes the flute to be nearer the tap axis at the tip of the tap than further back therefrom, this being in relationship to the angle of the forward cutting threads of the tap. Accordingly, the handle 59 can be operated to loosen the nut 58 and the turret then set at the desired angle to the axis of the tap as appears in FIG. 8. In the present context, this is called the horizontal angle. Then the handle 59 is again turned to tighten the nut 58 to retain the tap in that adjusted position. The screw 66 is loosened to permit the turret to be rocked about the axis until the tap has the proper angle -with respect to the angle of the tap threads, which may be called the vertical angle. In the foregoing adjustments, the horizontal angle can be indicated by the graduations 60 and the vertical angle by the graduations 68.

When the tap is initially inserted in the chuck, the knob is set so that the detent occupies the topmost hole as indicated in FIG. 7.

The knob 11-4 is turned until the cross head 110 adjusts the grinding wheel 121 to a height proper to grind the flute on the tap. Normally in making such a setting, the turret is moved forward and laterally until it comes directly under the bottom of the grinding wheel which then can be set at approximately a position to contact the tap. It will be understood that the depth of cut in any given operation is determined by the setting of the knob 114 and as grinding passes are successively made, adjustment of the knob may be made.

In the foregoing operation, the knob 48 will have been adjusted to slide the platen 40 and the turret mounted thereon laterally. There may be graduations on the knob 48 to indicate the lateral position, if desired. Fore-and-aft or in-and-out movement of the turret is always permitted and is effected by placing the hands on the platen or turret and moving it in and out to bring the tap under the grinding wheel. To prevent grinding parts that should not be ground, the limit stops 37 and 38 are adjusted to prevent any over-travel of the grinding wheel with respect to the other parts of the machine.

After one spiral point ute is ground, the tap is turned. The tap illustrated is one with three primary utes in it and so the knob 80 is turned 120, the detent 75 then engaging in the appropriate socket or hole. If the tap is one having two or four utes, the knob is turned accordingly and the detent will act when sufficient movement has been made.

If it is necessary to recalibrate the position of the tap With respect to the shaft, this can be done by loosening the screw 78 and then disposing the detent in the top socket at the time the tap flute is in the topmost position. After this the screw 78 is again tightened.

It will -be seen that when one ute has been ground, the only change necessary to grind subsequent utes is to turn the knob 80 and to make any necessary vertical adjustment of the grinding wheel by turning lthe knob 114. The angularity of the turret does not need to be changed.

The shape of the flute being ground is determined by the shape of the grinding wheel. As is evident, different grinding wheels may be placed on the motor shaft as desired. Also different sizes of taps can be ground on this machine. lIf the chuck being used is too small for the tap to be ground, then the screw 78 can be loosened and the collars 71 and 80 removed and a different shaft and different sized chuck inserted.

The machine has been described as being used for grinding spiral point flutes. It can be used for grinding any utes on taps, or even for grinding the so-called unfluted taps that have only a spiral flute or the like near their ends.

The apparatus should be made of well-machined, strong parts with limited tolerances, as is apparent from the necessities of its operation.

What is claimed is:

1. In a machine for grinding flutes in taps: a support, means on the support to hold a motor having a motor shaft, a rotatable grinding wheel on the motor shaft; means to adjust the motor and grinding wheel in a xed vertical path with respect to the support, including two horizontally spaced pairs of vertically spaced V-bearings, a pair of rods, one mounted in each pair of V-bearings, bars capping the opposite sides of the bearings and secured to the support whereby the rods are securely mounted on the support in parallel vertical positions, a cross head slideably mounted on the rods, the motor being mounted on the cross head and screw-type adjusting means connected between the cross head and the support for moving the cross head vertically on the rods; a tap holding head to hold the tap to be ground, the tap holding head including a collet device and means for holding the collet device on the head, the tap holding head having guide means mounting the head movably onto the support and to guide movement of the head and collet device in a direction perpendicularly to the axis of rotation of the grinding wheel and at a location to enable the tap to be moved into and out of engagement with the wheel; means for adjusting the collet device on the head about a vertical axis to change the angular relationship of a tap being ground to the axis of rotation of the grinding wheel, and means for adjusting the collet device on the head about a horizontal axis to change the angular relationship of a tap being ground to the horizontal, the tap holding head comprising a turret means to hold the collet, a shank below the turret means upon which the turret means is mounted for angular adjustment about a horizontal axis, a platen, the turret means being above the platen to dispose the collet device in open condition above the supportso that the tap can be readily received from above, means for supporting the shank on rthe platen for adjustment about a vertical axis, and the means mounting the head movably on the supportcomprising two horizontally spaced pairs of oppositely disposed V-notch bearings on the support, a pair of round rods, one disposed in each pair of V-notch bearings so as to dispose the round rods in parallel positions horizontally and in a plane parallel to the motor shaft axis, clamp blocks secured to the support to hold the round rods in the V- notch bearings, and frictionless bearings to support the platen on the round rods.

2. The machine of claim 1 and adjustable limiting means for limiting an extreme movement of the tap holding head on the round rods, to enable a tap to be moved only to a predetermined position with respect to the grinding wheel and to avoid grinding beyond that point.

3. The machine of claim 2 wherein the limiting means includes a member movable With the tap holding head and an adjustable member on the movable member and engageable against the support.

4. The machine of claim 1 wherein the collet device includes a collet and a collet holding portion in the form of a turnable shaft and means to support the same for rotation about the axis of the collet, and detent means to detain the collet holding portion in predetermined angular positions of adjustment corresponding to angular positions of utes of a tap, the detent means comprising a collar on the shaft and recesses and a resilient detent for releasably holding the shaft in selected positions, the collar being adjustably secured to the shaft to calibrate position of the collet.

5. The machine of claim 1 wherein the collet device includes a collet and a collet holding shaft and means to support the collet device for rotation about the axis of the collet, the collet holding shaft being removable for enabling collets of different sizes to be used.

vReferences Cited UNITED STATES PATENTS 587,537 8/ 1897 Van Norman. 1,434,131 10/1922 Lutz 51-92 2,040,709 5/ 1936 Pruitt 51-225 X 2,189,015 2/19'40 lMaurer 51-92 3,101,574 8/1963 West 51-92 LESTER M. SWINGLE, Primary Examiner 

